Different States have different laws. In some States, if you have a carry permit and have a weapon, YOU ARE REQUIRED to let the officer know as soon as you make contact, period. This is not whether or not you feel like telling him. If you don't tell him you just broke the law, plain and simple.
In other States, you do not have to let the officer know about your carry permit.
In the State of Florida, I DO NOT have to let the officer know, unless he asks. To me, common courtesy would be to tell the officer as soon as I make contact.
At the side of the road with a broken serpentine belt in Iowa an officer stopped and asked if I needed any assistance. I told him that I was armed, had a carry permit, and that I would appreciate if he just stayed behind me with his lights flashing while I changed the belt. No big deal and I was on my way in 20 minutes.
Get a book and learn the laws in States where you travel. The laws change almost yearly and to be safe, you need to keep up to date on what the current laws are in each State that you travel in.
It is also a good idea to always keep your license and insurance info within easy reach if you are carrying so that you DO NOT have to fumble around for it if stopped. This is sort of common sense since an officer standing beside your coach CANNOT see what you are doing.
Also in some States, carrying a weapon in your vehicle is LEGAL by anyone if it can be seen from the outside. Make sure that in your RV, the weapon is visible in those States, UNLESS you have a concealed carry permit.
Basically it all boils down to knowing the law in each state.